Wednesday, October 24, 2012

Prosopagnosia Research Center

Prosopagnosia Research Centers at Harvard University and University College London : Research

Prosopagnosia, also called face blindness, is an impairment in the recognition of faces. It is often accompanied by other types of recognition impairments (place recognition, car recognition, facial expression of emotion, etc.) though sometimes it appears to be restricted to facial identity. Not surprisingly, prosopagnosia can create serious social problems. Prosopagnosics often have difficulty recognizing family members, close friends, and even themselves. They often use alternative routes to recognition, but these routes are not as effective as recognition via the face.

History

Reports of prosopagnosia date back to antiquity, but Bodamer's report (1947) of two individuals was a landmark paper in that he extensively described the symptoms and declared it to be distinct from agnosia. He referred to their condition as prosopagnosia, which he coined by combining the Greek word for face (prosopon) with the medical term for recognition impairment (agnosia). Since that time, more than a hundred case reports have been published.

Symptoms of Prosopagnosia

Everyone sometimes has trouble recognizing faces, and it is even more common for people to have trouble remembering other people's names. Prosopagnosia is much more severe than these everyday problems that everyone experiences. Prosopagnosics often have difficulty recognizing people that they have encountered many times. In extreme cases, prosopagnosics have trouble recognizing even those people that they spend the most time with such as their spouses and their children.

One of the telltale signs of prosopagnosia is great reliance on non-facial information such as hair, gait, clothing, voice, and other information. Prosopagnosics also sometimes have difficulty imagining the facial appearance of acquaintances. One of the most common complaints of prosopagnosics is that they have trouble following the plot of television shows and movies, because they cannot keep track of the identity of the characters.

If you would like to assess your face recognition abilities, we currently have two tests of face recognition available. These tests include feedback on how your scores compare to the scores of people with normal face recognition.

Causes of Prosopagnosia

Most of the cases of prosopagnosia that have been documented have been due to brain damage suffered after maturity from head trauma, stroke, and degenerative diseases. These are examples of acquired prosopagnosia: these individuals had normal face recognition abilities that were then impaired. It seems likely that more cases of acquired prosopagnosia have been published for two reasons. First, their impairment with faces is usually quite apparent to these individuals, because they have experienced normal face recognition in the past and so they quickly notice their impairment. Second, because these individuals have had brain damage, they are in contact with medical doctors who have assessed their face recognition abilities. (Note that if you have experienced a noticeable decline in your face recognition abilities, you should contact a neurologist immediately. Any sudden decline may indicate the existence of a condition that needs immediate attention.)

In contrast, in cases of developmental prosopagnosia, the onset of prosopagnosia occurred prior to developing normal face recognition abilities (adult levels of face recognition are reached during teenage years). Developmental prosopagnosia has been used to refer to individuals whose prosopagnosia is genetic in nature, individuals who experienced brain damage prior to experience with faces (prenatal brain damage or immediate brain damage), and individuals who experienced brain damage or severe visual problems during childhood. However, these etiologies should be differentiated, because they are different paths to prosopagnosia and so probably result in different types of impairment; they could be referred to as genetic prosopagnosia, preexperiential prosopagnosia, and postexperiential prosopagnosia, respectively. In some cases, it may be difficult to determine the cause of prosopagnosia, but many times individuals will either know that family members are also prosopagnosic or be aware of potential incidents that may have resulted in brain damage.

Individuals with developmental prosopagnosia often do not realize that they are unable to recognize faces as well as others. Of course, they have never recognized faces normally so their impairment is not apparent to them. It is also difficult for them to notice, because individuals with normal face recognition rarely discuss their reliance on faces. As a result, there are a number of individuals who have not recognized their prosopagnosia until well into adulthood. We have been contacted by far more developmental prosopagnosics than acquired prosopagnosics, and so it may be that this condition is more common than acquired prosopagnosia.

Explanations

There are a variety of explanations for prosopagnosia. Of course, all these explanations propose that the procedures necessary for normal face recognition are not working properly. However, the explanations differ in their characterization of the impaired procedures. It appears that prosopagnosia actually refers to a number of different types of impairments, so no one explanation will account for all cases of prosopagnosia.

Research Questions

Currently, we have a very limited understanding of prosopagnosia, and so there are many research questions that need to be answered. Some of the leading questions are:

What is the nature of the procedures that are impaired in prosopagnosia?

What brain regions are impaired in prosopagnosia?

What genes are involved with genetically-based prosopagnosia?

Are there methods by which prosopagnosics can improve their face recognition?

The primary reason that we have such a limited understanding of prosopagnosia is that few prosopagnosics have been intensively investigated. This is especially true for developmental prosopagnosia. Recently, however, the internet has made it much easier for researchers and prosopagnosia to make contact, and it seems likely that we will see an increased amount of research in the near future.

If you believe that you are prosopagnosic or have other types of recognition impairments and are interested in becoming involved with research, please contact us using our form. We will try to get you involved with studies that we are conducting or we can put you in contact with researchers in your area. Studies typically involve three or four hours of assessment.

In addition to providing important data for research on prosopagnosia, prosopagnosics often find that they gain greater insight into their condition from testing. For example, we assess abilities with a variety of object types (horses, flowers, cars, etc.) and test other types of face processing (emotional expression recognition; sex, age, and attractiveness via the face; gaze direction determination). These are abilities that are often difficult to self-assess and realization of unknown impairments can often help individuals better cope with their impairment.